This is a progress report of an investigation concerning the construction of electroformed dental dies and casts from rubber impression materials. The four representative impression materials included: one mercaptan, two silicones, and one polyether. These elastomers were tested with the following five plating baths: low metal alkaline AgCN, acid CuSO4, potassium pyrophosphate, nickel chloride, high metal alkaline AgCN. Bath operating procedures included: bath pretesting and purification, continuous agitation, temperature elevation, well-controlled current density, pH, and filtration as recommended by electroplating authorities. Each impression material was tested in each bath (total 120 test specimens). The elastomer test specimen was a standardized flat surface 1 cm2 in area. Good elastomer/bath combinations included: high metal Ag CN with all four elastomers, Permlastic/low metal AgCN, Lastic 55/CuSO4, and Elasticon/NiCl2. The best elastomer/bath combinations were used for the production of clinically simulated dies. Die accuracy was tested by microscopically measuring the openings between master castings and the dies. Values so obtained from some electroformed dies were not significantly different from those of comparable stone dies.